text: The interchange of bridging and terminal ligands is called bridge-terminal exchange.  The process is invoked to explain the fluxional properties of metal carbonyl and metal isocyanide complexes.   Some complexes that exhibit this process are cobalt carbonyl and cyclopentadienyliron dicarbonyl dimer:
  :Co(μ-CO)(CO)    Co(μ-CO)(CO)(CO)
  :(CH)Fe(μ-CO)(CO)   (CH)Fe(μ-CO)(CO)
  These dynamic processes, which are degenerate, proceed via an intermediate where the CO ligands are all terminal, i.e. .